When doing renovation work, it is often necessary to make cutouts in either plaster or drywall (wallboard) walls. In many instances, the worker is unaware whether or not there are water pipes, gas pipes, or electrical or phone wires in the wall where the cutout is to take place. The normal and most cautious approach, therefore, is to make the cutout using hand tools such as a utility knife or keyhole saw. Such cutting is a difficult and tedious aspect of renovation work. If such cutting is attempted with a power tool, such as a reciprocating saw, however, there is a risk that the blade will cut deeply through the wall material and into the cavity of the wall where pipes, wires or studs are located, causing damage or danger. Reciprocating saws have a powerful, aggressive cutting action which is difficult to control. Thus, before attempting to cut with a reciprocating saw, the pipes, studs and wires behind the wall must normally be located by careful hand cutting.
Moreover, there are other problems in using a reciprocating saw for this type of cutting. For example, there is a lack of stability when making starting or "plunge" cuts into the material being cut. The saw blade has a tendency to whip from side to side when not engaged with the wall material, which can cause unwanted damage to paint or wallcoverings as the plunge cut is made. There is also a risk that, on a forward cutting stroke, the saw blade could hit on an unyielding object and cause the saw to jump suddenly and violently. It is also difficult to keep the saw blade accurately on a cut line when making a cut, particularly when the cut line crosses over a stud or joist or runs longitudinally over a stud or joist, where the blade is continuously striking the stud or joist causing the machine to "kick back" in the hands of the operator. It is not unusual to break the blade of a reciprocating saw when making this type of cut.
Lastly, the operator is limited in the positions and orientations in which a reciprocating saw can be used to make a cut. When using conventional reciprocating saws, the operator can install the blade in two possible positions, either right side up or upside down. To go from one position to the other, the blade must be changed to the new position. A cut may be made only in the direction of the blades' teeth, which is usually towards the operator. As noted, there is no way to accurately control the depth of the cut. A need therefore exists to improve the versatility and safety, and to accurately control the depth of cutting, of a conventional reciprocating saw.
Many devices shown in the prior art are capable of rotary cutting action using a circular blade. It has also been suggested to modify certain power tools to accomplish different additional functions. For example, U.S. Pat. No. 4,361,956 to Kirk shows modification of a saber saw to provide oscillating motion to a blade.
Insofar as is known, it has not been suggested in the art to modify a reciprocating saw to expand its versatility and overcome the difficulties described above.